Multiple Sclerosis is an inflammatory, demyelinating and neurodegenerative disorder of the central nervous system (brain, spinal cord and optic nerve) of unknown etiology. It is the leading cause of non-traumatic disability among young and middle-aged adults, and it affects 2.3 million people worldwide about two-thirds of those affected are women. Multiple Sclerosis has various courses depending on clinical progression. The most common one, the Relapsing-remitting form is characterized by clearly defined attacks of new or increasing neurologic symptoms. Most people who are diagnosed with Relapsing-remitting form will eventually transit to a secondary progressive course in which there is a progressive worsening of neurologic function (accumulation of disability) over time. Primary progressive form which is the most severe one is defined by worsening neurologic function and accumulation of disability from the onset of symptoms, without early relapses or remissions. Over time, the body's capacity to repair myelin may diminish; neurological damage no longer reverses itself and permanent lesions remain. Multiple Sclerosis may touch a lot of different central nervous system spots that lead to a multitude of signs and symptoms, among them motor and vision impairments; cognitive and psychological problems may also be present. During the past two decades our understanding of multiple sclerosis pathophysiology has radically changed and has led to the development of treatments for the disease, which delay its natural course and the onset of disability. Nevertheless, there is no cure for this disease today. Various treatment options available today have been shown to decrease the frequency of relapses and disease progression. This thesis work gives as an introduction some historical elements that had helped to understand the pathophysiology and the disease evolution as it is known nowadays. Then in the first main part it goes through the disease characteristics (origins, risk factors and immunological disorder). Finally the last part describes the actual disease modifying therapies that can be prescribed to slow the course of the disease.